"Emmanuel Gustin" wrote in message ...
"Kevin Brooks" wrote in message
om...

When did the USN switch to the 20mm during WWII, or for that matter
during the Korean War?

Right after WWII, when the M3 version of the Hispano became
available. Delivery of the F8F-1B was to begin in April '46,
simultaneous with that of the F4U-5. The F2H and F9F also
had four M3 cannon. (The F2H-3 had Mk.12 guns). Of the less
successful (to use a heavy understatement) types the FJ-1 had
.50 guns, but the F6U-1 had 20 mm cannon.

The USAF did use M24 cannon (a modified M3) in B-36
bombers and in early F-89 nightfighters, but USAF day fighters
did not switch to cannon until the Pontiac M39 became available,
i.e. in the 'Century Series' fighters. Yes, the F-86H-5 and later
models also had four M39 cannon, but the first of these was
delivered in early 1955; it was contemporary with the F-100A.

The USAAF had cannon armed fighters, or partially armed, fighters well
before that--see the P-38 and P-39.

Actually, a small number of cannon armed Sabres (12, IIRC) were combat
tested in Korea, but problems (induced compressor stalls) were found
with that early arrangement and the program was shelved.


shifting to the 20mm at roughly the same time (in the same general
timeframe that the A-1 was coming into major service with its 20mm,

The AD-1 entered service in December 1946, slightly later
than the cannon-armed USN fighters.

The USN, or at least the USMC, was still using its MG armed Corsairs
into the Korean conflict (yes, some F4U-4 series had 20mm, but they
were a minority, as was the AU-1).

Brooks